Method and apparatus for component concentration in the vapor phase



Aug. 5, 1969 Filed Dec. 9. 1966 RAW GAS IN J. R. SPENCER E AL IN THEVAPOR PHASE 2 Sheets-Sheet. l

vs V I3 6 l4 7 9 IO H vs vs 3.4 4-

l8 a a a m m m n: 8 3 w o a 0 -l9 1 GAS COOLER -24 GAS HEATER VII BLOWER29 RESIDUE GAS 4 44 42 3sv GAS TO GAS B OW HEAT EXCHANGER 39 ENRICHEDGAS IN VEN TORS JOHN R. SPENCER WALTON D. GREATHOUSE JAMES H. CHEEKAGENT g- 5, 1969 J. R. SPENCER ET AL 3,458,973

METHOD AND APPARATUS FOR COMPONENT CONCENTRATION IN THE VAPOR PHASEe'zva 7 IO -M a v9 24 GAS HEATER via V I5 -30 Filed Dec. 9. 1966 2Sheets-Sheet 2 RAW GAS IN ABSORBER k GAS TO GAS BLOWER HEAT EXCHANGER 2ov|9 vzo ENRICHED GAS HEAVY ENDS REJECTION FIG. 2 I

IN VENTORS JOHN R. SPENCER WALTON D. GREATHOUSE JAMES H. CHEEK UnitedStates Patent us. or. 5562 v 21 Claims ABSTRACT OF THE DISCLOSURE Acyclical method and apparatus for separating intermediate molecularweight hydrocarbon gases (ethane and ethylene) from primarily methanegas are disclosed. The feed stream of methane, ethane and ethylene gasis flowed through a sorbent bed where ethane and ethylene are adsorbedto a point of saturation. The saturated bed is then desorbed of ethaneand ethylene by heating it in a closed heating circuit. As gas pressurein the heating circuit increases, part of the gas therein is bled fromthe circuit yielding a gas product enriched in ethane and ethylene. Atthe end of the heating or desorption step the heated bed is cooled by astream of cool gas before being returned to the ethane-ethylene sorptionstep. A continuous operation is maintained by cycling three or more bedsthrough the sorption, heating and cooling phases.

This invention relates to the separation of intermediate molecularWeight hydrocarbons from a gas stream. More specifically, this inventionis concerned with the recovery of ethane from natural gas streams andwith the recovery of ethane and ethylene from refinery gas streams.

Many hydrocarbon gas streams are processed to recover the propane andhigher molecular weight hydrocarbons present. The intermediate molecularweight hydrocarbons, particularly ethane and ethylene, now also havebecome of importance as a source of raw material for certain chemicalsyntheses. Often, however, even though the ethane and ethylene fractionsof these hydrocarbon gas streams are substantial, these fractions arenot recovered because of the expense of the required equipment. Therecovery methods most commonly used now are based essentially onabsorbing ethane and ethylene in a cold oil sorbent and subsequentlyrecovering the ethane and ethylene by regenerating the liquid sorbent.But again, cold oil absorption techniques are disadvantageous in thatthey require a great amount of expensive refrigeration equipment.Obviously, method and apparatus for recovering ethane and ethyleneoperating at or near atmospheric temperature will have advantages.

It is an object of this invention to present an improved method ofrecovering intermediate molecular weight hydrocarbons from hydrocarbongas streams.

Another object of this invention is to present a method and apparatusfor recovering intermediate molecular weight hydrocarbons which requirea minimum of refrigeration equipment. I

Another object of this invention is to present method and apparatus forrecovering ethane and ethylene from hydrocarbon gas streams byadsorption at or near atmospheric temperatures.

Another object of this invention is to present method and apparatus forseparating ethane and ethylene from hydrocarbon gas streams which areetficient and economical.

Other aspects, objects, and advantages of our invention will becomeaparent from the following disclosure, the claims, and the accompanyingfigures. FIGURE 1 presents schematically one embodiment of applying ourin- Patented Aug. 5, 1969 ventive method and apparatus. FIGURE 2presents schematically a second embodiment.

In brief, our invention provides a cyclical method and apparatus forrecovering intermediate molecular weight gases, such as ethane andethylene, from a gas stream by adsorbing intermediate molecular Weightgases cyclically in one of a plurality of beds of solid sorbent; anotherspent bed of solid sorbent (saturated with ethane and/or ethylene) isregenerated by circulating through it a heated regeneration gas in aclosed heating or regenerating circuit. As this sorbent bed is heated,the ethane and ethylene are desorbed from the sorbent and become part ofthe circulating regenerating gas, thereby causing the pressure in theclosed regeneration circuit to increase. When pressure in the heatingcircuit reaches a predetermined value, a portion of the circulating gasis removed to maintain the predetermined pressure as heating andregenerating is continued. This gas stream removed is a mixture rich inethane and ethylene and is a desired product of our method andapparatus.

It will be understood that the raw gas treated must consist primarily ofethane, ethylene, methane, and other inerts, with only traces of highermolecular weight hydrocarbons such as propane, butane, etc. Sources ofsuch streams are natural gas from subterranean hydrocarbon reservoirsand petroleum refiney processing steams.

The method of our invention will now be described as embodied in andwith reference to FIGURE 1. Raw gas, such as natural gas, containing anintermediate molecular weight hydrocarbon (ethane) to be recovered,flows into the system by way of conduit 1 to one of the adsorbers 16,17, and 18. The adsorbers are filled with a sorbent material, forexample, activated carbon, capable of removing the intermediatemolecular weight hydrocarbons from the raw gas stream. Let it be assumedthat adsorber 16 is on stream, although during latter phases conduits 3and 4 will serve to conduct gas to adsorbers 17 and 18, respectively.The raw gas, in flowing through adsorber 16, is stripped of ethane. Theresidual gas flows from adsorber 16 by way of conduit 22 and is removedfrom the system. In subsequent phases of the cycle, conduits 23 and 24will serve similarly to remove gas from adsorbers 17 and 18,respectively. In summary, the adsorption step of the method comprisesflowing a raw gas through a sorbent body, thereby removing all or partof the intermediate molecular weight gas, for example ethane, in the gasand flowing the stripped residue gas from the sorbent body.

When the sorbent material in an adsorber becomes spent or saturated withethane, it must be regenerated by passing through it a heated gas todesorb the adsorbed ethane. Let it be assumed that adsorber 18 is in theprocess of being heated and regenerated. A heated gas, obtained prior tobeginning the heating step, from the residue gas stream flowing fromanother adsorber in the adsorption step of the method, flows by way ofconduits 11, 7, 14, and 4 to adsorber 18. Conduits 11, 5, 12, and 2, and11, 6, 13, and 3 serve a similar purpose when adsorbers '16 and 17 areregenerated. The heated gas flowing through adsorber 18 heats thesorbent material therein and causes the adsorber ethane to be desorbed.The gas stream flows from adsorber 18 by way of conduits 24, 34, and 27into conduits leading to the gas heater. Conduits 22, 32, and 25, and23, 33, and 26 serve a similar purpose when adsorbers 16 and 17 arebeing heated. As the temperature of the regenerating gas circulatingthrough adsorber 1-8 and that of the sorbent therein increases, thepressure within adsorber 18, heater 19, the interconnecting conduits andother equipment, increases substantially. When this pressure rises abovea predetermined value, gas in the regeneration circuit is bled offthrough conduit 36 and valve V19 sufficiently to maintain pressure inadsorber 18 and heater 19 at the predetermined level. The gas thusremoved is a concentration of ethane and is a desired product of themethod. In summary, the regeneration step of the method comprisescirculating a heater regeneration fluid through a spent sorbent bed in aclosed circuit and removing gas enriched in ethane from the circuit tomaintain a predetermined pressure in the circuit.

When a sorbent body has been heated sufficiently to remove the adsorbedethane, it must be cooled before it can function again as a sorbent. Letit be assumed that adsorber 17 is to be cooled. The source of coolinggas is part or all of the residue gas stream flowing through conduit 44.This stream is diverted through conduit 46 and flows through a blower 21and cooler 20. The cooling gas then flows through conduits 15, 9, 13,and 3 into adsorber 17, and from adsorber 17 through conduits 23, 33,29, and 38 and returns to the residue gas stream 44. In summary, thecooling step of the method comprises diverting a portion of the residuegas stream from the adsorbing step, cooling the diverted stream, andpassing it through the bed to be cooled.

As shown in FIGURE 1, it is desirable to flow the effiuent gas from thebed being cooled in heat exchange with gas in the heating circuitthrough a heat exchanger 41.

After heating a sorbent bed to a condition where the adsorbed andabsorbed ethane is vaporized, the heated bed and associated conduits arefilled with a gas rich in ethane. It is desirable to retain this gaswithin the system. At the same time, another spent sorbent bed must beplaced in the regeneration step. To increase the efficiency of ourmethod, therefore, the gas in the hot adsorber is displaced into thecold adsorber that is about to be regenerated by heating. A portion ofresidue gas from the adsorber in the sorption circuit is diverted andflowed into the hot regenerated bed and the conduits associatedtherewith. Simultaneously, gas in the cold spent adsorber is displacedback into the residue gas stream. As shown in FIGURE 1, assuming thatadorber 18 is hot and adsorber 16 is about to be placed in theregeneration circuit, adsorber 17 would be switched into the adsorptionstep and a portion of the efliuent residue gas from adsorber 17 flowingin conduit 44 would be diverted through conduits 46, 47, 15, 10, 14, and4 through the hot regenerated bed 18. Since there is directcommunication between adsorber 18 and adsorber 16 by way of conduits 24,34, 27, 31, 35, 45, 43, 40, heater 19, conduits 11, 5, 12, and 2, acertain volume of gas will be displaced from adsorber 16 through conduit22. This displaced gas is a lean, stripped gas and is discarded in theresidue gas line 44.

The apparatus of our invention will now be described as embodied in andwith reference to FIGURE 1.

The apparatus comprises a minimum of three circuits, a sorption circuit,a cooling circuit, and a heating or regenerating circuit. The sorptioncircuit comprises a raw gas inlet manifold coupled with the threesorbent beds which in turn are coupled with an exit residue gasmanifold. In FIGURE 1, conduit 1 and conduits 2, 3, and 4 in conjunctionwith valve V1, V2, and V3, respectively, make up the inlet gas manifoldand control the flow of raw gas into the adsorbers 16, 17, and 18.Similarly, conduits 22, 23, and 24 intersecting with conduit 44 andinterrupted by valves V16, V17, and V18, respectively, comprise theresidue gas outlet manifold and control the flow of gas from theadsorbers 16, 17, and 18 when each of these is in the sorption circuit.

Thus, if it be assumed that adsorber '16 is connected in the sorptioncircuit, valves V1 and V16 would be open and valves V2, V3, V4, V7, V10,and V13 would be closed so that raw gas may fiow through conduits 1 and2, adsorber 16, conduits 22 and 44.

The heating or regenerating circuit comprises inlet and outlet manifoldscoupled with the three sorbent beds, a compressor, optionally a heatexchanger, and a gas heater.

In FIGURE 1, conduit 11 and conduit 5, 6, and 7 interrupted by valvesV4, V5, and V6 comprise the inlet heating gas manifold, which connectswith the gas heater 19 and by conduits 12 and 2, 13 and 3, and 14 and 4,with adsorbers 16, 17, and 18, respectively. Conduits 25, 26, and 27,interrupted by valves V10, V11, and V12, and conduits 31 and 35 make upthe exit heating gas manifold. The manifold is connected to theadsorbers 16, 17, and 18 by conduits 32 and 22, 33 and 23, and 34 and24, respectively, and communicates through conduit 45, compressor 42,conduit 43, heat exchanger 41, and conduit 40 with gas heater 19. Thus,if it is assumed that adsorber 18 is connected in the heating circuit,valves V6 and V12 will be open and valves V3, V4, V5, V9, V10, V11, V15,and V18 will be closed. Heating gas can then circulate from the gasheater 19 through conduits 11, 7, 14, 4, adsorber 18, conduits 24, 34,27, 31, 35, 45, compressor 42, conduit 43, heat exchanger 41, conduit40, and back to gas heater 19. Conduit 36 and valve V19 are alsoconnected into the heating circuit. As adsorber bed 18 is regenerated,pressure in the heating circuit will increase. Whne the pressure reachesa predetermined value, gas is bled off through valve V19 and conduit 36to maintain the predetermined pressure value. The gas removed isenriched in ethane when processing a natural gas stream and is one ofthe desired products of the apparatus. Valve V19 can be madeautomatically responsive to the pressure in the heating circuit, openingand closing to maintain the desired pressure.

The cooling circuit comprises inlet and outlet cooling gas manifoldscoupled with the three sorbent beds, a compressor or blower (ifdesired), and gas cooler. As shown in FIGURE 1, conduit 15 and conduits8, 9, and 10 interrupted by valves V7, V8, and V9 make up the coolinggas inlet manifold which connects with cooler 20 and through conduits 12and 2, 13 and 3, and 14 and 4 with adsorbers 16, 17, and 18,respectively. Conduits 28, 29, and 30 interrupted by valves V13, V14,and V15 and conduit 38 make up the cooling gas outlet manifold which isconnected by conduits 32 and 22, 33 and 23, 34 and 24 with adsorbers 16,17, and 18, respectively, and communicates through heat exchanger 41 andconduit 39 with the residue gas conduit 44. Thus, if it is assumed thatadsorber 17 is connected in the cooling gas conduit, valves V8 and V14will be open and valves V2, V5, V7, V9, V11, V13, V15, and V17 will beclosed. Gas will then fiow from the residue gas line 44 through conduit46, the blower 21, conduit 47, gas cooler 20, conduits 15, 9, 13, and 3,adsorber '17, conduits 23, 33, 29, and 38, heat exchanger 41, conduit39, and back to the residue gas line 44.

As discussed above, when a hot sorbent bed is converted from the heatingcircuit to the cooling circuit, the gas present in the hot bed isdisplaced into the spent adsorbent bed by a volume of gas taken from theresidue gas line. Assume adsorber 18 is to be switched from the heatingcircuit to the cooling circuit and adsorber 16 is to be switched to theheating circuit when adsorber 17 is switched to the sorption circuit.Under these conditions, valves V2, V4, V9, V12, V13, and V17 are openand valves V1, V3, V5, V6, V7, V8, V10, V11, V14, V15, V16, V18, and V19are closed. Raw gas will then flow through conduits I and 3, adsorber17, and the residue gas flow through conduits 23 and 44. A portion ofthe residue gas will be diverted through conduit 46, blower 21, conduit47, gas cooler 20, conduits 15, 10, 14, 4, and into adsorber 18;correspondingly, gas in adsorber 18 will be displaced through conduits24, 34, 27, 31, 35, 45, blower 42, conduit 43, heat exchanger 41,conduit 40, heater 19, conduits 11, 5, 12, and 2 into adsorber 16. Gaswill flow from adsorber 16 through conduits 22 32, 12 8, heat exchanger41, and conduit 39 to residue gas ine At the end of this displacement orpurge step, the approprtate valves are opened and closed to continue thenext cycle of adsorbing, heating, and cooling the adsorbers.

Alternatively, the efiluent gas from the adsorber about to beregenerated can be returned to the residue gas line by Opening the valvein the residue gas outlet manifold from the bed and closing the valve inthe cooling gas outlet manifold. For example, in the precedingdescription of valve opening and closing during purging, valve V16 wouldbe opened and valve V13 would remain closed. This flow path will bypassthe heat exchanger 41 and may be advantageous in some cases.

A complete schedule of the opening and closing of valves is presented inTable I for three cycles.

TAB LE I ABSORBER AND VALVE SEQUENCE Absorber: I

16 Sorbing Purging Heating Purging Cooling Sorbing 17 Cooling SorbingSorbing Purging Heating Purging 18 Heating Purging Cooling SorbingSorblng Purging Valves:

C C C C O O O C C C C C O O C O C C C C C 0 0 C C C C C 0 C C O O C C CC C O O O C C C C O O C C C C C O 0 O C C C C O C C C O C C C O C C C CO C C O C C O C C C O O 0 C O C C C C 0 O C O Vl9 O 2 C O 2 C O 3 CAbbreviations: C=va1ve closed; O=valve opened.

An alternate sequence is indicated in the right-hand column for eachpurge step for valves V13 to V18.

2 Opened to maintain predeterlmned maximum pressure 1n heating circuit.At the end of three cycles, each of the sorbent beds has transferredthrough each circuit and is ready to resume 1ts first function. Theswitching of each bed from one circuit to another can be controlled by atime cycle mechanism or by temperature sensing mechanisms. Thetemperature sensing mechanisms are preferred. For example it may bedesirable to place a temperature sensing element in the conduits leadingfrom the heating circuit so that when the temperature of a bed in theheating circuit reaches a predetermined value, as indicated by thetemperature of heating gas flowing from that bed, a new cycle can bestarted. Activated carbon is preferred for the sorbent material used inthe sorbent beds.

FIGURE 2 depicts a second embodiment of our method and apparatus. Mostof the elements of FIGURE 2 are identical to those in FIGURE 1 and sohave been given identical numeral designations in FIGURE 2. In FIG- URE2, the adsorption circuit is the same as in FIGURE 1. The heatingcircuit has been modified b adding a second release conduit 48 withvalve V20, which is discussed below. The cooling circuit has beenmodified in that the position of the gas cooler 20 and blower 21 havebeen reversed, and valve V21 has been interposed between the two.Further, a conduit 49 now connects the upstream side of'the valve V21 tothe residue gas line 44 and another conduit 50 the downstream side ofthe valve V21 to the residue gas line 44.

In the method depicted in FIGURE 2, the schedule for the valves of TableI remains the same; the adsorp tion and heating steps also are the sameas described for FIGURE 1. Valve V20 remains closed and valve V21 open.The step of cooling, however, is conducted by recycling the cooling gasthrough the bed being cooled in a semi-closed cooling circuit. Conduits49 and 50 are connected to the cooling circuit to permit additional gasto enter the cooling circuit from the residue gas line as coolingprogresses and the gas volume in the cooling circuit shrinks.

For example, if it is assumed adsorber 17 is being cooled, cooling gaswill flow from the compressor 21 through conduits 15, 9, 13, and 3,adsorber 17, conduits 23, 33, 29, and 38, heat exchanger 41, conduit 51,gas cooler 20, conduit 52, valve V21, conduit 53, and back to the blower21. Conduits 49 and 50 connect the cooling circuit to the residue gasline, and gas flows through these conduits in quantity sutficient tocompensate for shrinkage of gas volume in the cooling circuit.

In the purge or displacement step, the gas volume in the heated bed isdisplaced by circulating, in a semiclosed cycle, gas from the bed aboutto be heated into the bed about to be cooled, and simultaneously, gasfrom the bed to be cooled into the bed to be heated. For example, if itis assumed adsorber 1 8 is to begin cooling an adsorber 16 is to beginheating, then gas will be flowed through blower 21, conduit 15, valveV9, conduits 10, 14, and 4, into adsorber 18, and from adsorber 18through conduits 24, 34, conduit 27, valve V12, conduits 31, 35, 45,blower 42, conduit 43, heat exchanger 41, conduit 40, heater 19, conduit11, valve V4, conduits 5, 12, 2, adsorber 16, conduits 22, 32, valveV13, conduits 28, 38, heat exchanger 41, conduits 51, cooler 20, valveV21, conduit 52, conduit 53, and back to blower 21.

During the latter part of the displacement step, it may be desirable todisplace the latter portion of the gas displaced from the hot adsorbercompletely from the system. This gas may contain traces of heavierhydrocarbons which, if displaced into the cold adsorber about to beregenerated, would tend to accumulate within the system. These heavierhydrocarbons are the last to be desorbed in regenerating the spentsorbent and are the last to be displaced from the sorbent as the purgestep proceeds. This secondary purge step is accomplished by openingvalve V20 and closing valve V21 and venting the effluent gas from thebed being purged from the system. Thus, for FIGURE 2, the flow path ofgas will be from conduit 44 through conduit 50 and blower 21, conduit15, valve V9, conduits 10, 1-4, 4, adsorber 18, conduits 24, 34, 27,valve V12, conduits 31, 35, 45, blower 42, conduits 43, 48, and valveV20. This gas removed can be treated to remove the heavy hydrocarbons ifdesirable. This secondary purge step is optional and in many cases maynot be necessary. A valve program showing the valve positions for theembodiment of FIGURE 2, including the secondary or subpurge step, ispresented in Table H.

TABLE II ABSORBER AND VALVE SEQUENCE Adsorber:

16 Sorbing Purging Heating Purging Cooling Sorbing 17 Cooling SorbingSorbing Purging Heating Purging 18 Heating Purging Cooling SorbingSorbing Purging Valves:

V C C C C C C 0 O O O 0 C C C C C C C C O 0 0 C C O O O C C C C C C C C0 O 0 C C C C C C C C O 0 C C C O O O C C C C C C C C O O 0 O 0 C C C CC C C O O O C C C C C C C C O 0 O O O C C C C C C O C C C C 0 C C C C CO C C C C C C O C C C 0 C C C C C C C O 0 O O O C C C C C C C C 0 O O CC C C O a C C 0 2 C C C 0 C C O C C 0 V21 0 0 C O O C O 0 0Abbreviations: C=valve closed; O=valve opened. 1 Sequence in rightcolumn is for subpurge step at end of purge step. 2 Opened to maintainpredetermined maximum pressure in heating circuit.

EXAMPLE to the next in response to a gas-temperature sensing point inthe adsorber being reactivated when the gas-temperature reaches 400 F.Feed gas in conduit 1 is at about 100 F. and 820 p.s.i.g. in an amountof about 20 MM c.f./day (measured at 60 F. and 14.65 p.s.i.a.) Adsorbervessels 16, 17, and 18 each have a volume, empty, of 592 ft. and operateat a pressure of about 810-830 p.s.i.a. Each adsorber contain about16,200 lbs. of activated carbon (8-10 mesh). Temperature of the sorbentmaterial is about 110 F. during adsorption, a maximum of about 450 F.and an average of about 375 F. during reactivation, and is cooled toabout 120 F. during the cooling phase. Residue gas in an amount of about18,800 M c.f./day at about 115-125 F. and 800 p.s.i.a. is produced byway of conduit 44. Reactivation gas is circulated in conduit 11 in anamount of about 13,500 M c.f./day at about 450 F. and 812 p.s.i.a.Reactivation gas in conduit 45 is maintained at a predetermined pressureof about 806 p.s.i.a. by bleeding off gas through valve V19 in an amountof about 1,200 M c.f./day. Gas in conuduit 15 has a temperature of about120 F. and in conduit 39 (FIGURE 1) has a temperature of about 175 F.and flows through conduit 15 (FIGURE 1) or conduit 49 (FIGURE 2) in anamount of about 20,000 M c.f./day. Heater 19 is designed for a duty of6,600,000 B.t.u./hr. and 1,000 p.s.i.g.

Average compositions in mole percentages at various points throughoutthe system are tabulated below:

Carbon Propane Conduit N2 dioxide Methane Ethane plus The wordssorption, sorbent, adsorb, etc., are used herein to connote thephenomena of adsorption and/ or absorption.

Having thus described our invention by providing specific examplesthereof, it is to be understood that no undue limitations orrestrictions are to be drawn by reason thereof and that many variationsand modifications are within the scope of the invention.

What is claimed is:

1. Apparatus for removing sorbable components from a hydrocarbon gasstream comprising:

(a) a plurality of vessels containing a solid sorbent;

(b) a heater;

(c) a cooler;

(d) gas circulating means;

(e) a plurality of first conduits conducting said hydrocarbon gas streamto said vessels (a);

(f) a plurality of second conduits communicating between said vessels(a) and a first point of utility;

(g) a plurality of third conduits communicating between said vessels (a)and said heater (b);

(h) a plurality of fourth conduits communicating between said vessels(a) and said gas circulating means (i) a fifth conduit communicatingbetween said gas circulating means ((1) and said heater (b);

(j) a gas releasing means communicating between a second point ofutility and a circuit consisting of said heater (b), at least one ofconduits (g), at least one of vessels (a), at least one of conduits (h),gas circulating means (d), and conduit (i);

(k) a plurality of sixth conduits communicating between said vessels (a)and said cooler (c);

(l) a plurality of seventh conduits communicating between said vessels(a), said first point of utility (f), and said cooler (c); and

(m) valve means in each of said plurality of first, second, third,fourth, sixth, and seventh conduits of (e), (f), (g), (h), (k), and (1),respectively.

2. The apparatus of claim 1 and a gas-to-gas heat exchangercommunicating between said plurality of conduits (l) and said point ofutility of (e) and communicating between one of said vessels (a) andsaid heater (b).

3. The apparatus of claim 1 wherein said gas releasing means (j) is avalve.

4. The apparatus of claim 1 wherein said gas releasing means (j) is avalve responsive in action to the gas pressure in the circuit of (j).

5. The apparatus of claim 1 and a gas circulating means communicatingbetween said cooler (c) and said plurality of vessels (2.).

6. Apparatus for removing sorbable components from a hydrocarbon gasstream comprising:

(a) a plurality of vessels containing a solid sorbent;

(b) a heater;

(c) a cooler;

(d) gas circulating means;

(e) a plurality of first conduits conveying said gas stream of saidvessels (a);

(f) a plurality of second conduits communicating between said vessels(a) and a first point of utility;

(g) a plurality of third conduits communicating between said vessels (a)and said heater (b);

(h) a plurality of fourth conduits communicating between said vessels(a) and said gas circulating means (i) a fifth conduit communicatingbetween said gas circulating means (d) and said heater (b);

(j) a gas releasing means communicating between a second point ofutility, and a circuit consisting of said heater (b), at least one ofconduits (g), at least one of said vessels (a), at least one of conduits(h), gas circulating means (d), and conduit means (i);

(k) a plurality of sixth conduits each communicating at one end withsaid vessels (a);

(l) a plurality of seventh conduits communicating between said saidvessels (a) and one end of said cooler (m) a valve communicating, whenopened, between a second end of said cooling means (c) and the other endof each of said plurality of sixth conduits (k);

(u) an eighth conduit communicating between one end of said valve (m),said second end of said cooling means (c), and said first point ofutility of (f);

(o) a ninth conduit communicating between a second end of said valve(m), said plurality of conduits (f and said plurality of conduits (k);and

(p) valve means in each of said plurality of first, second, third,fourth, sixth and seventh conduits of (g) and respectively- 7. Theapparatus of claim 6 and a gas-to-gas heat exchanger communicatingbetween said plurality of conduits (l) and said cooler (c) andcommunicating between one of said vessels (a) and said heater (b).

8. The apparatus of claim 6 and a second gas releasing means (q)communicating between a third point of utility and the circuit of (j).

9. The apparatus of claim 8 wherein said gas releasing means (j) and (q)are each a valve.

10. A method of separating ethane and ethylene gas from a gas streamcomprising ethane, ethylene, and methane, and containing only traces ofhigher molecular weight hydrocarbons comprising:

(a) contacting a solid sorbent body with said gas stream, therebyadsorbing said ethane and ethylene gas onto said solid sorbent body;

(b) contacting said solid sorbent body with a heated flowing gas in aclosed circuit, thereby desorbing said solid sorbent body of ethane andethylene gas into said flowing gas;

(c) withdrawing a portion of said heated gas of (b) containing desorbedethane and ethylene gas as product from said closed circuit;

(d) returning the remaining poriton of said heated gas to contactingsaid solid sorbent body in step (b);

(e) purging said sorbent body of heated gas; and

(f) contacting said sorbent body with a cool gas, thereby cooling saidsorbent body to a temperature suflicient to repeat step (a).

11. The method of claim wherein the heated gas of (b) is circulated inheat exchange relationship with the cool gas of step (f).

12. In the method for removing ethane and ethylene gas from a gasmixture comprising ethane, ethylene, and methane, and containing onlytraces of higher molecular weight hydrocarbon gases, utilizing thecontact of solid sorbent material with the gas mixture, with resultantadsorption of the ethane and ethylene gas by the solid sorbent materialand the subsequent treatment of the solid sorbent material with a heatedgas to desorb and remove the adsorbed ethane and ethylene gas and tothereby regenerate a solid sorbent material for further contact with thegas mixture, the improvement which comprises:

(a) maintaining at least one bed of solid sorbent material in each of aplurality of zones;

(b) continuously heating and flowing gas in a closed circuit through atleast one of said beds of sorbent material to desorb ethane and ethylenegas contained on the sorbent in said bed, and to heat the sorbentmaterial in said bed;

(c) removing a portion of said heated gas of (b) from said closedcircuit;

(d) returning the remaining portion of said heated gas to the heatingand flowing step of (b);

(e) continuously directing a flow of cool gas through at least anotherone of said beds of sorbent material to cool said sorbent bed;

(f) directing a rflow of gas containing ethane and ethylene gas throughan additional one of said beds of sorbent material to remove said ethaneand ethylene gas from said gas by sorption in said bed; and

(g) periodically shifting the relative positions of the beds of sorbentmaterial and the flow of gases in each of said beds so that each bed ofstep (a) is heated as in (b), cooled as in (d), and contacted with gasas in (f).

13. The method as set forth in claim 12 wherein after a sorbent bedbeing heated has become desorbed of ethane and ethylene gases adsorbedtherein, the heated gas present in said bed is displaced into anothersorbent bed subsequently to be heated, and simultaneously the gaspresent in that latter sorbent bed is displaced therefrom, therebyconserving the desorbed ethane and ethylene gases contained in saidheated gas.

14. The method as set forth in claim 12 wherein said portion of heatedgas removed from said closed circuit in step (c) is removed at a ratesuificient to maintain a predetermined pressure in said closed circuit.

15. The method of claim 12 wherein after the sorbent bed of step (b) hasbecome desorbed of ethane and ethylene gases, the volume of heated gasthen present in said bed of step (b) is displaced into the sorbent bedof step (f) and the volume of gas then present in said bed of step (f)is displaced therefrom into said sorbent bed of step (b).

16. The method of claim 12 wherein after the sorbent bed of step (b) hasbeen desorbed of ethane and ethylene gases, a first portion of theregeneration gas in said bed of step (b) is displaced into the sorbentbed of step (f) and a second portion of the regeneration gas in said bedof step (f) is discharged independently of said sorbent beds of steps(b), (d), and (f).

17. The method of claim 12 wherein the gas of step (b) is flowed in heatexchange relationship with the cool gas of step (e).

18. The method of claim 12 wherein the gas removed from said gas mixtureis ethane.

19. The method of claim 12 wherein the gas removed from said gas mixtureis ethylene.

20. The method of claim 12 wherein said gas mixture is a natural gasstream.

21. The method of claim 12 wherein said gas mixture is a refinery gasstream.

References Cited UNITED STATES PATENTS 3,055,157 9/1962 Lavery et al.-62 X 3,080,692 3/ 1963 Staley et al. 55-62 X 3,186,144 6/1965 Dow 5562X 3,266,221 8/1966 Avery 55-62 X 3,324,669 6/1967 Cooper et al 55-62 X3,311,189 7/1967 Worley 55-62 REUBEN FRIEDMAN, Primary Examiner I. ADEE,Assistant Examiner US. Cl. X.R.

